This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. Scavenger receptors are pattern recognition receptors that bind and traffic a variety of endogenous and microbial ligands. The broad objective of our current studies is to define the mechanisms by which scavenger receptors modulate, and can be targeted to modulate, immune responses from leukocytes. Specifically, we are investigating: 1) how Scavenger Receptor Class-A (SR-A) functions to internalize bacteria and chaperones into antigen-presenting cells, and 2) how SR-A -expressing leukocytes contribute to ovarian cancer. A large part of our effort is directed towards Aim 1, which evokes from our identification of SR-A as a novel endocytic receptor for the molecular chaperones gp96 and CRT. With the use of SR-A-/- mice we have focused on elucidating the mechanisms by which scavenger receptors mediate the immunological effects of chaperones. Recent data on this project were published in Bak et al. (2008) and Tewalt et al. (2008). Our studies have recently expanded to identify the role of SR-A during bacterial infection with the use of dendritic cells (DCs) from SR-A-/- mice. Functional analyses elucidated a novel interplay between SR-A and the Toll-like receptors (TLR) for DC internalization of the gram-negative bacteria E. coli (Amiel et al., 2009). Current efforts are now directed at extending these investigations to the bacteria Pseudomonas aeruginosa, which is a bacterial pathogen that substantially contributes to the pathogenesis of cystic fibrosis (CF) patients. The COBRE-funded studies described in this Abstract formed the basis for our subsequently-funded NIH RO1 grant.